During operation of a wavelength division communication system, main optical power should ensure a power budget for system design, so as to ensure normal operation of a receiver. Meanwhile, in order to avoid influence of capacity expansion or addition or reduction operation of wavelength channels on existing service transmission, an optical amplifier in the system may need to work in a gain-clamped state. During operation of the system, if an attenuation of an optical fiber is changed by aging of the optical fiber or other factors, power of an optical signal of a service may be changed, and even the service may be interrupted in a severe case.
In order to avoid influence of a change in the attenuation of the optical fiber on service transmission, the wavelength division communication system may need to have an automatic power regulation function. That is, when the attenuation of the optical fiber is changed, an attenuation of an attenuator in the system may be automatically regulated or a gain of the amplifier may be regulated, so as to maintain the power budget for system design. An ordinary APO subsystem may be implemented on a network management system. Because the network management system is a multi-task operating system, an implementation mechanism of the APO subsystem on the network management system should be a regular query mechanism. If a regular query interval is too short, a large number of resources of the network management system may be occupied, which may easily cause crash of the network management system as well as low practicability for a practical project. But if the regular query interval is too long, a response speed for a change in the main optical power may be low, resulting in low execution efficiency.